The ability to regenerate disease-destroyed tissue is an important goal in many medical situations. It is especially significant in the mineralized tissues that maintain the structural integrity of the organism. The process of guided tissue regeneration (GTR) is an important advance in dentistry because it fosters regeneration of at least four tissue types in a functioning organ, the periodontal attachment apparatus, that has previously been destroyed by disease. Because this clinical result has been empirically derived, a more basic approach is needed to identify the regenerative cells, examine their regulation, and apply this information to enhance the regenerative process. Underlying the GTR process is the recruitment of progenitor cells from damaged tissues that are capable of producing the new organ. The exclusion of gingival connective tissue and epithelium is thought to be critical. These cells are excluded by placing an inert membrane around the neck of the tooth to cover the underlying the bone and periodontal ligament. Progenitor populations from the tissue beneath the membrane are then allowed to repopulate the area of destroyed tissue. Our hypothesis is that a subset of these cells is capable of producing or being induced to produce mineralized tissue. We have retrieved clinical samples of these membranes and have established the cells adherent to and enmeshed in them in culture. Our specific aims are to (1) characterize regenerative cell populations on these membranes by evaluating their similarity to osteoblasts (2) examine the heterogeneity of these populations by quantitating the numbers of bone progenitors (3) identify new or unique proteins associated with these clones. These experiments will characterize cells associated with bone induction by guided tissue regeneration and establish cell lines that will be used to study mechanisms of bone formation and mineralization in general. Subsequent studies will utilize these cell lines in experiments that may suggest ways to enhance results from GTR.